Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-26T19:40:41.500Z Has data issue: false hasContentIssue false
  • English
  • Français

Conodont palaeothermometry of contact metamorphism in Middle Ordovician rocks from the Precordillera of western Argentina

Published online by Cambridge University Press:  27 March 2008

GUSTAVO G. VOLDMAN ,
GUILLERMO L. ALBANESI  and
MARGARITA DO CAMPO
GUSTAVO G. VOLDMAN*
Affiliation:
CONICET and Museo de Paleontología, Universidad Nacional de Córdoba, P.O. Box 1598, X5000FCO Córdoba, Argentina
GUILLERMO L. ALBANESI
Affiliation:
CONICET and Museo de Paleontología, Universidad Nacional de Córdoba, P.O. Box 1598, X5000FCO Córdoba, Argentina
MARGARITA DO CAMPO
Affiliation:
INGEIS (CONICET – UBA) and Universidad Nacional de Buenos Aires, 1428 Buenos Aires, Argentina
*
§Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The Yerba Loca Formation (Middle–Upper Ordovician), exposed in the Western Precordillera, San Juan, Argentina, is made up of clastic–carbonate turbidites, and basic–ultrabasic rocks. It is affected by regional Siluro-Devonian very low-grade metamorphism that locally reaches greenschist facies. At Ancaucha creek, 45 conodont samples were taken from two sections that include 30 to 50 m thick sills. In order to analyse the thermal alteration patterns produced by these intrusive bodies, conodont Colour Alteration Index (CAI) is contrasted with optical petrography and X-ray diffraction analyses of clay minerals. The intrusions are dated as post-Darriwilian (Da2), as determined by conodont biostratigraphy of the host rock, which indicates the Paroistodus horridus Subzone of the Lenodus variabilis Zone. The distribution of CAI values defines a thermal aureole of about 2.5 times intrusion thickness that prevailed over the later very low-grade metamorphism. Metasomatism at Ancaucha creek is recorded by CAI values of 4 to 7, particularly restricted to a few layers close to the intrusions, as indicated by conodont textures and rock fabric. One-dimensional thermal computer simulation conforms to empirical data indicating temperatures greater than 600 °C for the contact zone, although it points out slightly narrower thermal aureoles. The clay mineral assemblage of most of the analysed samples (chlorite, illite, smectite and I/S mixed-layers) is complex and probably derives from several superimposed processes, thus representing non-equilibrium assemblages. In turn, KI values (0.27–0.32) indicate anchizone metamorphism, in agreement with regional CAI values of 4; consequently, the occurrence of smectite and I/S probably resulted from retrograde diagenesis processes.

Keywords

conodontCAIclay mineralogycontact metamorphismOrdovicianPrecordilleraArgentina
Type
Original Article
Information
Geological Magazine , Volume 145 , Issue 4 , July 2008 , pp. 449 - 462
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abre, P., Zimmermann, U., Cingolani, C., Cairncross, B. & Chemale, F. Jr. 2006. Nd isotopes from Yerba Loca Formation (Upper Ordovician), Cuyania terrane, Argentina. In V South American Symposium on Isotope Geology, Punta del Este. Short papers (eds Bossi, J., Gaucher, C. & Campal, N.), pp. 201–3. El Palomar, Buenos Aires: Facultad de Agronomia, Facultad de Ciencias, Universidad de la Republica.Google Scholar
Albanesi, G. L., Hünicken, M. A. & Barnes, C. R. 1998. Bioestratigrafía de conodontes de las secuencias ordovícicas del Cerro Potrerillo, Precordillera Central de San Juan, R. Argentina. Actas de la Academia Nacional de Ciencias, Córdoba 12, 7–72.Google Scholar
Albanesi, G. L., Ortega, G. & Hünicken, M. A. 1995. Conodontes y graptolitos de la Formación Yerba Loca (Arenigiano–Llandeiliano) en las quebradas de Ancaucha y El Divisadero, Precordillera de San Juan, Argentina. Boletín de la Academia Nacional de Ciencias, Córdoba 60, 365–400.Google Scholar
Alvarez-Marron, J., Rodriguez-Fernandez, R., Heredia, N., Busquets, P., Colombo, F. & Brown, D. 2006. Neogene structures overprinting Palaeozoic thrust systems in the Andean Precordillera at 30°S latitude. Journal of the Geological Society, London 163, 949–64.CrossRefGoogle Scholar
Armstrong, H. A. & Strens, M. R. 1987. Contact meta-morphism of conodonts as a test of colour alteration index temperatures. In Conodonts: Investigative Techniques and Applications (ed. Austin, R. L.), pp. 203–8. Chichester: Ellis Horwood Limited.Google Scholar
Blasco, G. & Ramos, V. 1976. Graptolitos caradocianos de la Formación Yerba Loca y del Cerro La Chilca – Departamento Jáchal, provincia de San Juan. Ameghiniana 13, 312–29.Google Scholar
Buggisch, W., Gosen, W. Von, Henjes–Kunst, F. & Krumm, S. 1994. The age of Early Paleozoic deformation and metamorphism in the Argentine Precordillera – evidence from K–Ar data. Zentralblatt Geologie und Paläentologie Teil 1, 275–86.Google Scholar
Burnett, R. D. 1988. Physical and chemical changes in conodonts from contact-metamorphosed limestones. Irish Journal of Earth Sciences 9, 79–119.Google Scholar
Cuerda, A., Cingolani, C. A. & Varela, R. 1983. Las Graptofaunas de la Formación Los Sombreros, Ordovícico inferior, de la vertiente oriental de la Sierra del Tontal, Precordillera de San Juan. Ameghiniana 20, 239–60.Google Scholar
Cunningham, C. G., Austin, G. W., Naeser, C. W., Rye, R. O., Ballantyne, G. H., Stamm, R. G. & Barker, C. E. 2004. Formation of a Paleothermal Anomaly and Disseminated Gold Deposits Associated with the Bingham Canyon Porphyry Cu–Au–Mo System, Utah. Economic Geology 99, 789–806.CrossRefGoogle Scholar
Davis, J. S., Roeske, S. M., McClelland, W. C. & Snee, L. W. 1999. Closing the ocean between the Precordillera terrane and Chilenia: Early Devonian ophiolite emplacement and deformation in the southwest Precordillera. In Laurentia–Gondwanan Connections before Pangea (eds Ramos, V. A. & Keppie, J. D.), pp. 115–38. Boulder, Colorado: Geological Society of America, Special Paper no. 336.Google Scholar
Ellison, S. 1944. The composition of conodonts. Journal of Paleontology 18, 133–40.Google Scholar
Epstein, A. G., Epstein, J. B. & Harris, L. D. 1977. Conodont color alteration – An index to organic metamorphism. United States Geological Survey Profes-sional Paper 995, 1–27.Google Scholar
Fernández-Noia, E. A., Sumay, C. A. & Meissl, E. F. 1990. Petrografía de los cuerpos magmáticos del Ordovícico de las sierras de la Yerba Loca y del Alto de Mayo – San Juan – Argentina. In XI Congreso Geológico Argentino, San Juan. Actas 1 (ed. Comisión Editorial, 17–21 septiembre 1990), pp. 48–51. San Juan: Universidad Nacional de San Juan.Google Scholar
Flügel, E. 2004. Microfacies of Carbonate Rocks. Analysis, Interpretation and Application. Berlin, Heidelberg, New York: Springer-Verlag, 976 pp.Google Scholar
Furque, G. 1963. Descripción Geológica de la Hoja 17b – Guandacol (Provincias de La Rioja–San Juan). Boletín Dirección Nacional de Geología y Minería, Buenos Aires 92, 1–104.Google Scholar
Furque, G. 1979. Descripción Geológica de la Hoja 18c, Jáchal. Boletín Servicio Geológico Nacional, Buenos Aires 164, 1–81.Google Scholar
Furque, G. 1983. Descripción Geológica de la Hoja 19c, Ciénaga de Gualilán, Provincia de San Juan. Boletín Servicio Geológico Nacional, Buenos Aires 193, 1–111.Google Scholar
Galushkin, Y. I. 1997. Thermal effects of igneous intrusions on maturity of organic matter: A possible mechanism of intrusion. Organic Geochemistry 26, 645–58.CrossRefGoogle Scholar
García-López, S., Bastida, F., Aller, J. & Sanz-López, J. 2001. Geothermal palaeogradients and metamorphic zonation from the conodont colour alteration index (CAI). Terra Nova 13, 79–83.CrossRefGoogle Scholar
Gleason, J. D., Finney, S. C., Peralta, S. H., Gehrels, G. E. & Marsaglia, K. M. 2007. Zircon and whole-rock Nd–Pb isotopic provenance of Middle and Upper Ordovician siliciclastic rocks, Argentine Precordillera. Sedimentology 54, 107–36.CrossRefGoogle Scholar
Gosen, W. Von. 1992. Structural evolution of the Argentine Precordillera: the Río San Juan section. Journal of Structural Geology 14, 643–67.CrossRefGoogle Scholar
Gosen, W. Von. 1997. Early Paleozoic and Andean structural evolution in the Rio Jáchal section of the Argentine Precordillera. Journal of South American Earth Sciences 10, 361–88.CrossRefGoogle Scholar
Guggenheim, S., Bain, D., Bergaya, F., Brigatti, M., Drits, V., Eberl, D., Formoso, M., Galán, E., Merriman, R., Peacor, D., Stanjek, H. & Watanabe, T. 2002. Report of the Association International pour L'Etude Des Argiles (AIPEA) Nomenclature Committee for 2001; Order, Disorder and Crystallinity in Phyllosilicates and the use of the ‘Crystallinity Index’. Clays and Clay Minerals 50, 406–9.CrossRefGoogle Scholar
Haller, M. J. & Ramos, V. A. 1984. Las ofiolitas famatinianas (eopaleozoico) de las provincias de San Juan y Mendoza. In IX Congreso Geológico Argentino, San Carlos de Bariloche. Actas 2 (ed. Editorial, Comisión, 5–9 noviembre 1984), pp. 66–83. Buenos Aires: Asociación Geológica Argentina.Google Scholar
Harris, A. G., Rexroad, C. B., Lierman, R. T. & Rosemary, A. A. 1990. Evaluation of a CAI anomaly, Putnam County, Central Indiana, U.S.A.: Possibility of a Mississippi Valley-Type Hydrothermal System. Courier Forschungsinstitut Senckenberg 118, 253–66.Google Scholar
Jordan, T. E., Allmendinger, R. W., Damanti, J. F. & Drake, R. E. 1993. Chronology of motion in a complete thrust belt: the Precordillera, 30–31°S, Andes Mountains. Journal of Geology 101, 135–56.CrossRefGoogle Scholar
Kay, S. M., Ramos, V. A. & Kay, R. W. 1984. Elementos mayoritarios y trazas de vulcanitas ordovícicas de la Precodillera Occidental: basaltos de rift oceánico temprano (?) próximos al margen continental. In IX Congreso Geológico Argentino, San Carlos de Bariloche. Actas 2 (ed. Editorial, Comisión, 5–9 noviembre 1984), pp. 48–65. Buenos Aires: Asociación Geológica Argentina.Google Scholar
Kisch, H. J. 1991. Development of slaty cleavage and degree of very-low-grade metamorphism. Journal of Metamorphic Geology 9, 735–50.CrossRefGoogle Scholar
Königshof, P. 1991. Conodont colour alteration adjacent to a granitic intrusion, Harz mountains. Neues Jahrbüch für Geologie und Paläontologie H2, 84–90.CrossRefGoogle Scholar
Königshof, P. 2003. Conodont deformation patterns and textural alteration in Paleozoic conodonts: examples from Germany and France. Senckenbergiana lethaea 83 (1/2), 149–56.CrossRefGoogle Scholar
Kovács, S. & Árkai, P. 1987. Conodont alteration in metamorphosed limestones from northern Hungary, and its relationship to carbonate texture, illite crystallinity and vitrinite reflectance. In Conodonts: Investigative Techniques and Applications (ed. Austin, R. L.), pp. 209–29. Chichester: Ellis Horwood Limited.Google Scholar
Kübler, B. 1967. La cristallinité de l'illite et les zones tout á fait supérieures du métamorphisme. In Etages Tectoniques (ed. Neuchâtel, Colloque de, 18–21 avril 1966), pp. 105–21. A la Baconniére, Neuchâtel: Université Neuchâtel.Google Scholar
Merriman, R. J. & Frey, M. 1999. Patterns of very low-grade metamorphism in metapelitic rocks. In Low-grade metamorphism (eds Frey, M. & Robinson, D.), pp. 61–107. London: Blackwell Science Limited.Google Scholar
Nabelek, P. I. 2002. Calc-silicate reactions and bedding-controlled isotopic exchange in the Notch Peak aureole, Utah: implications for differential fluid fluxes with metamorphic grade. Journal of Metamorphic Geology 20, 429–40.CrossRefGoogle Scholar
Nicoll, R. S. 1981. Conodont colour alteration adjacent to a volcanic plug, Canning Basin, Western Australia. BMR Journal of Australian Geology & Geophysics 6, 265–7.Google Scholar
Nicoll, R. S. & Gorter, J. D. 1984. Conodont colour alteration, thermal maturation and the geothermal history of the Canning basin, Western Australia. The APEA Journal 24, 243–58.Google Scholar
Nieto, F., Mata, P. M., Bauluz, B., Giorgetti, G., Árkai, P. & Peacor, D. R. 2005. Retrograde diagenesis, a widespread process on a regional scale. Clay Minerals 40, 93–104.CrossRefGoogle Scholar
Nieto, F. & Peacor, D. R. 1993. Regional retrograde alteration of prograde lower grade hydrated assemblages. Terra Abstracts 5, 419.Google Scholar
Ortega, G., Albanesi, G. L. & Frigerio, S. E. 2007. Graptolite and conodont faunas of early Darriwilian age (Middle Ordovician) in the Cerro Viejo succession, San Juan Precordillera, Argentina. Palaeogeography, Palaeoclimatology, Palaeoecology 245, 245–63.CrossRefGoogle Scholar
Ortega, G., Brussa, E. & Astini, R. 1991. Nuevos hallazgos de graptolitos en la Formación Yerba Loca y su implicancia estratigráfica, Precordillera de San Juan, Argentina. Ameghiniana 28, 163–78.Google Scholar
Pinkerton, H., James, M. & Jones, A. 2002. Surface temperature measurements of active lava flows on Kilauea volcano, Hawaii. Journal of Volcanology and Geothermal Research 113, 159–76.CrossRefGoogle Scholar
Quartino, B. J., Zardini, R. A. & Amos, A. J. 1971. Estudio y exploración geológica de la región Barreal-Calingasta. Buenos Aires: Asociación Geológica Argentina, Monografía no. 1, 184 pp.Google Scholar
Ramos, V. A. 1988. The tectonics of the Central Andes; 30° to 33°S latitude. In Processes in Continental Lithospheric Deformation (eds Clark, S. & Burchfiel, D.), pp. 31–54. Boulder, Colorado: Geological Society of America, Special Paper no. 218.CrossRefGoogle Scholar
Ramos, V. A., Cristallini, E. O. & Pérez, D. J. 2002. The Pampean flat-slab of the Central Andes. Journal of South America Earth Sciences 15, 59–78.CrossRefGoogle Scholar
Ramos, V. A., Escayola, M., Mutti, D. I. & Vujovich, G. I. 2000. Proterozoic–early Paleozoic ophiolites of the Andean basement of southern South America. In Ophiolites and Oceanic Crust: New Insights from Field Studies and the Ocean Drilling Program (eds Dilek, Y., Moore, E. M., Elthon, D. & Nicolas, A.), pp. 331–49. Boulder, Colorado: Geological Society of America, Special Paper no. 349.Google Scholar
Ramos, V. A., Jordan, T. E., Allmendinger, R. W., Kay, S. M., Cortes, J. M. & Palma, M. 1984. Chilenia: Un terreno alóctono en la evolución paleozoica de los Andes centrales. In IX Congreso Geológico Argentino, San Carlos de Bariloche. Actas 2 (ed. Editorial, Comisión, 5–9 noviembre 1984), pp. 84–106. Buenos Aires: Asociación Geológica Argentina.Google Scholar
Ramos, V. A., Jordan, T. E., Allmendinger, R. W., Mpodozis, C., Kay, S. M., Cortés, J. M. & Palma, M. 1986. Paleozoic terranes of the central Argentine–Chilean Andes. Tectonics 5, 855–80.CrossRefGoogle Scholar
Rejebian, V. A., Harris, A. G. & Huebner, J. S. 1987. Conodont color and textural alteration: An index to regional metamorphism, contact metamorphism, and hydrothermal alteration. Geological Society of America Bulletin 99, 471–9.2.0.CO;2>CrossRefGoogle Scholar
Repetski, J. E. & Narkiewicz, M. 1996. Conodont color and surface textural alteration in the Muschelkalk (Triassic) of the Silesian–Cracow Zn–Pb district, Poland. In Carbonate-hosted zinc and lead deposits in the Silesian-Cracow area, Poland (eds Górecka, E., Leach, D. L. & Kozlowski, A.), pp. 113–20. Warsaw: Polish Geological Institute.Google Scholar
Robinson, D. 1971. The inhibiting effect of organic carbon on contact metamorphic recrystallization of limestones. Contributions to Mineralogy and Petrology 32, 245–50.CrossRefGoogle Scholar
Robinson, D., Bevins, R. E. & Rubinstein, N. 2005. Subgreenschist facies metamorphism of metabasites from the Precordillera terrane of western Argentina; constraints on the later stages of accretion onto Gondwana. European Journal of Mineralogy 17, 441–52.CrossRefGoogle Scholar
Sangster, D. F., Nowlan, G. S. & McCracken, A. D. 1994. Thermal comparison of Mississippi Valley–type Lead–Zinc deposits and their host rocks using fluid inclusion and conodont color alteration index data. Economic Geology 89, 493–514.CrossRefGoogle Scholar
Simoneit, B. R. T. 1994. Organic matter alteration in hydrothermal systems. In Geofluids: Origin, Migration and Evolution of Fluids in Sedimentary Basins (ed. Parnell, J.), pp. 261–74. London: Geological Society of London, Special Publication no. 78.Google Scholar
Stone, J. 1987. Review of investigative techniques used in the study of conodonts. In Conodonts: Investigative Techniques and Applications (ed. Austin, R. L.), pp. 17–34. Chichester: Ellis Horwood Limited.Google Scholar
Suchý, V., Šafanda, J., Sýkorová, I., Stejskal, M., Machovič, V. & Melka, K. 2004. Contact metamorphism of Silurian black shales by a basalt sill: geological evidence and thermal modeling in the Barrandian Basin. Czech Geological Survey Bulletin of Geosciences 79, 133–45.Google Scholar
Teichmüller, M. 1987. Organic material and very low-grade metamorphism. In Low Temperature Metamorphism (ed. Frey, M.), pp. 114–98. New York: Blackwell.Google Scholar
Turcotte, D. L. & Schubert, G. 2002. Geodynamics: Applications of Continuum Physics to Geological Problems. New York: John Wiley & Sons, 450 pp.CrossRefGoogle Scholar
Villa, I. M. 2001. Geothermometers, Arrhenian behaviour and ‘geothermometers’. Terra Nova 13, 84–5.CrossRefGoogle Scholar
Warr, L. N. 1996. Standardized clay mineral crystallinity data from the very low-grade metamorphic facies rocks of southern New Zealand. European Journal of Mineralogy 8, 115–27.CrossRefGoogle Scholar
Warr, L. N. & Rice, A. H. N. 1994. Interlaboratory standardization and calibration of clay mineral crystallinity and crystallite size data. Journal of Metamorphic Geology 12, 141–52.CrossRefGoogle Scholar
Webby, B. D., Cooper, R. A., Bergström, S. M. & Paris, F. 2004. Stratigraphic framework and time slices. In The Great Ordovician Biodiversification Event (eds Webby, B. D., Paris, F., Droser, M. L. & Percival, I. G.), pp. 41–7. New York: Columbia University Press.CrossRefGoogle Scholar
Wohletz, K., Civetta, L. & Giovanni, O. 1999. Thermal Evolution of the Phlegraean Magmatic System. Journal of Volcanology and Geothermal Energy 91, 381–414.CrossRefGoogle Scholar
Wohletz, K. & Heiken, G. 1992. Volcanology and Geothermal Energy. Berkeley: University of California Press, 432 pp.Google Scholar
Yoder, H. S. & Tilley, C. E. 1962. Origin of basalt magmas: an experimental study of natural and synthetic rock systems. Journal of Petrology 3, 342–532.CrossRefGoogle Scholar